Pumping apparatus for refrigerator systems



Dec. 11, 1962 c. P. woon, JR

PUMPING APPARATUS FOR REFRIGERATOR SYSTEMS 3 Sheets-Sheet 1 Filed July6, 1960 INV N TOR. BY l1? I9 T TO/E YS- Dec. 11, 1962 c. P. wooD, JR3,067,590

PUMPING APPARATUS FOR REFRIGERATOR SYSTEMS INV EN TOR.

1977 ORNE YS.

COMPRESSOR Dec. 11, 1962 Q P. woon, JR 3,067,590

PUMPING APPARATUS FOR REFRIGERATOR SYSTEMS Filed July 6, 1960 5Sheets-Sheet 3 2 l 10@ zo j 1m 4 e $5 wmf @4 o 1 1% 120 f 112: 1a

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' INVENTOR.

#d njw ha United States Patent O 3,667,599 PUMPHNS APPARATUS FRREFRIGERATDR SYSTEMS Charles P. Wood, Jr., 459 Fairview Place,Cincinnati 19, @hic Filed July 6, 19ml, Ser. No. 41,086` 7 Claims.l (1462-335) This invention relates to refrigeration systems of theindustrial type and is directed particularly to an improvement involvingthe use of a refrigerant-powered pump for increasing the coolingcapacity and efficiency of the system.

One of the primary objectives of the present invention has been toprovide a simple liquid-powered pumping apparatus which takes advantageof the kinetic energy of the high pressure liquid refrigerant flowing ina high pressure portion of the refrigerating system to advance liquidrefrigerant at a lower pressure toward the evaporator in an automaticmanner, thereby to improve the cooling capacity of the system.

Briefly, a refrigerating system for which the present invention isintended includes essentially a compressor, a condenser wherein thecompressed refrigerant gas is liquilied by heat exchange, a highpressure receiver connected to the condenser, an accumulator which actsas a reservoir for storing a. supply of the liquid refrigerant advancedfrom the receiver, and one or more evaporators connected withtheaccumulator. The accumulator includes a liquid level control valve whichmaintains a given Volume of liquid refrigerant under low pressure foradvancement to the evaporator or evaporators, wherein the liquidrefrigerant expands and thereby absorbs heat.

That portion of the system between the compressor and liquid levelcontrol valve of the accumulator is under high pressure through themetering action of the liquid level control valve. On the other hand,the space in the accumulator above the liquid level is connected withthe intake side of the compressor to carry the heat-laden refrigerantgas from the evaporators back to the compressor for recirculation;hence, the accumulator is maintained Iunder a lower pressure. As aconsequence, in a conventional system, the liquid refrigerant from theaccumulator ows toward the evaporators under low pressure which isdeveloped usually by gravity,- the accumulator being mounted at anelevation above the evaporator.

According to the present invention, the liquid-powered pump takesmechanical advantage of the high pressure liquid refrigerant which isbeing forced by the condensing pressure into the accumulator andutilizes the energy thereof to4 force the lowfpressure liquidrefrigerant from the accumulator to the evaporators. Otherwiseexpressed, the apparatus essentially comprises a positive displacementliquid-powered motor, which is interposed in the high pressure lineleading from the compressor to the accumulator, combined with a directlycoupled pump of the positive displacement type interposed in the lowpressure line leading from the accumulator to the evaporators.

ln practicing the invention, the liquid-powered pump may be any one ofseveral types, such as a reciprocating, pulsating or rotary pump, and inthe present disclosure, which has been selected to bring out theprinciples of the invention, a motor-pump unit is utilized comprising arotary, positive displacement motor coupled directly to a rotary,positive displacement pump. The motor is interposed in the high pressureline which advances the liquidl refrigerant from the high pressureliquid receiver to the accumulator under control of the liquid levelcontrol valve of the accumulator, while the pumpY is interposed in the y3,067,599 Patented Dec'. I 1 1 9622 opens to admit high pressure liquidrefrigerant to the accumulator, theadvancing liquid refrigerantenergizesv the motor, which in turn drives the pump which is interposedin the supply line'to the evaporators so as to force the low pressureliquid refrigerant under positive displacement to the evaporators,thereby taking advantageof the kinetic energy which is imparted t'o theliquid high pressure refrigerant by the compressor.

Another objective of the invention has been to provide a self-containedmotor and pump unit of the rotary, posi-4 tive displacement type,wherein the pump provides a substantially greater cubic displacement perrevolution than= the motor which is directly coupledto it, thereby torelate`| the quantity of liquidflowing under vhigh pressure toward theaccumulator, to. the quantity' of liquid being forced. under lowpressure toward the evaporators.

In the embodiment whichhas been selected to illustrate the principles ofthe invention, the pump and motor eachcomprise a gear type unit, whereina pair of intermeshing gears is `enclosed within a casing whichincludes` a cavity enclosing the gears-and providing a running fit.y Inthe case of the motor, the high pressure liquid refrigerant isintroduced into one side of the cavity causing rotation of the gears;the fluid being exhausted from ther opposite side of the cavity.l One ofthe motor gears is mounted. upon a drive shaft which is directlyconnectedto oneof the pump gears soy as to drive the-pump at a one-l`to-one ratio. The pump gears are similar to the motor gears but aresubstantially larger to provide greater cubic pumping displacement perrevolution than thevolume'oi high pressure liquid driving the motor.

According to another aspect oftheinvention, the motorv and pumpcomprises avself-contained unit, the motor Aandpumpbeing joined insealed `relationship by a'shaft hous ing, thearrangement being suchthaty any leakageofgas? or liquid refrigerant about: the shaft of thepump or motor is trapped within the unit so= as to prevent contaminationof the atmosphere through leakage; In4 the preferred em.-A bodiment, thesealed shaft housing is provided withy an exhaust conduit which.communicates with the upper por' tion of the evaporator, which ismaintained under low" pressure. As a consequencel any leakage, whethergas or liquid, is drawn by suction into the accumulator for'recirculation throughout the refrigerating system.

A further objective .of this invention has been -to im?! prove Itheefficiency and cooling capacity of a condensing! cycle refrigerationsystem having .primary and secondary" stages,v as distinguished fromthezrnore conventional 're' circulating system. The condensing cyclesystem is of particular advantage Where lowertemperatures are re-'quired and where space is limited, and hasthe further ad= vantage ofeliminatingoil from the secondary stagewhich; when presen-t in thesystem, forms a lm' on the internalI surfaces of the evaporators andactsas an insulator whi-ch retards the chilling, action. When applied to thecondensing cycle system, the motor is interposed in the highipressureliquid refrigerant line of the primary stage,.whichE line.supplies the high pressure'liquid refrigerant to thel accumulator. Onthe other hand, the pump which is coupled to the motor, is interposedyin the line of the` second stage which supplies liquidi refrigerantunder` lowl pressure to the evaporators. Themotor is thus driven;y bythe kinetic energy which is conferredto the refrigerantl by thecompressor ofthe primary stage.

T hel secondary stage has nocompressor andis mechanically isolatedfrom'the primary stage, the heat fromthe evaporators 'being transferredto the primary stageL through a heat exchanger which communicates withthe' primary stage. Therefore, any lubricatingy oil which may escapefrom the compressor is completely isolated from the secondary stageevaporators. As high pressure liquid refrigerant is advanced to theaccumulator of the primary spense@ stage, liquid powered motor isenergized so as to drive the pump which is interposed in the lowpressure supply conduit at the secondary stage, thus forcing the lowpressure liquid refrigerant toward the evaporators to increase theefficiency of the system.

The various features and advantages of the invention will be more fullyapparent to those skilled in the art from the following detaileddescription taken in conjunction with the drawings.

In the drawings:

FIGURE 1 is a diagrammatic view showing a refrigeration system of therecirculation type embodying the refrigerant-powered motor and pumpapparatus of the present invention.

FIGURE 2 is a diagrammatic view of a condensing cycle type ofrefrigeration system embodying the motor and pump apparatus of thisinvention.

FIGURE 3 is an enlarged side view, partially in cross section, detailinga gear type motor and pump unit suitable for use in practicing theinvention.

FIGURE 4 is a sectional view taken along 4-4 of FIGURE 3,'furtherdetailing the motor-pump structure.

FIGURE 5 is a sectional View taken along line 5--5 of FIGURE 3,detailing the flexible coupling which interconnects the motor and pump.

Recz'rculatng System The refrigerating apparatus shown in FIGURE 1,which has been selected to illustrate the principles of the invention,represen-ts a typical industrial installation which is known in theindustry as a recirculation system. An industrial system of thischaracter is adapted to a wide variety of uses and may cool or chill anumber of compartments or rooms, each having its own evaporator tomaintain a desired temperature. Liquid ammonia is most widely used as arefrigerant in industrial systems of this type and the invention isdisclosed in relation to an ammonia system; however, it will beunderstood that the principles of the invention may be utilized insystems using refrigerants other than ammonia and operating underpressures and temperatures other than those which are specied by way ofexample herein.

Referring to FIGURE 1, the recirculation type system is powered by amotor-driven compressor 1, which is connected to a condenser indicatedgenerally at 2 by way of a conduit 3. It is to be noted at this point,that the compressor and other components of the system, as hereinafterdisclosed, and the circuit itself, generally follow conventionalpractice. The heat-laden refrigerant is supplied in the form of a gas tothe compressor 1 by way of a suction line 4 which extends from theaccumulator, as explained later, and upon being compressed, therefrigerant is advanced under high pressure to the condenser 2 still ingaseous form but under a higher pressure. In a typical system of thischaracter, the compressed gas may be under a pressure in theneighborhood of 185 p.s.i. and at a temperature in the neighborhood of250 F. as it is advanced from the compressor 1 toward the condenser 2.

The condenser 2, as illustrated, is of the water-cooled type comprisinga coil 5 enclosed in a tank 6, cold water being circulated through thetank by way of the lines 7 and 8 so as to carry off heat from theammonia gas passing through the coil 5. As the ammonia gas passesthrough the condenser 5, it is cooled and converted to liquid ammonia,which ows by way of the conduit 10 to a high pressure receiver 11, theliquid being maintained in the receiver under high pressure but at alower temperature. In the present example, the pressure within thereceiver also is in the neighborhood of 185 p.s.i., the temperaturehaving been reduced by the condenser 2 to approximately 85 F. The highpressure receiver is partially filled with liquid refrigerant and itsupper portion acts as a gas cushion to maintain the liquid ammonia underhigh pressure and at a given liquid level to be advanced to anaccumulator 12 by a conduit 13, which draws off the high pressure liquidfrom the bottom of the receiver 11 as at 14. The line 13 passes throughthe wall of the accumulator 12 and communicates with the upper end of asub-cooling coil 15 mounted within the accumulator, such that the warmliquid ammonia under pressure flows downwardly, as indicated by thearrows. After passing through the sub-cooling coil 15, the liquidammonia ows from the accumulator 12 by way of line 16 to the motor-pumpunit 17, consisting of a motor 1ndicated generally at 18 which isdirectly coupled to a pump, indicated generally at 20.

The high pressure liquid refrigerant line 16 communicates directly withthe motor 18 for driving the pump, as explained later in detail; afterpassing through the motor, the liquid refrigerant advances by way ofline 21 to a'liquid level control device, such as a oat valve, asindicated generally at 22, which communicates with the accumulator 12.As indicated diagrammatically, float valve 22 comprises a flow controlvalve 23 having a oat 24 residing within the shell 25 of the accumulator12 and arranged to maintain the ammonia within the accumulator at theliquid level indicated at 26. From the foregoing, it will be observedthat the high pressure liquid ammonia from the receiver I1 rst passesthrough the sub-cooling coil 15 within the accumulator, wherein heatexchange lowers the temperature of the incoming liquid to prevent theliquid from flashing into gas as it passes through the motor, afterwhich the cooled liquid refrigerant passes by way of line 16 to drivethe motorpump unit 17 before being delivered to the accumulator shell 25under control of the float valve 22. It will also be noted that the oatvalve 22 meters the flow of liquid refrigerant and, in so doing,develops the high back pressure in the lines 13 and 21.

The purpose of the accumulator is to maintain a supply of liquidrefrigerant to be advanced to the evaporators 27 and 23, wherein theliquid ammonia is allowed to expand and thus absorb heat; theaccumulator also acts as a collector for the expanded and excessunevaporated refrigerant returning from the evaporators. The liquidrefrigerant is advanced under low pressure from the bottom of theaccumulator to the evaporators by way of the conduit 30 whichcommunicates with the motor-driven pump 20. After passing through thepump, which acts as a booster, as explained later, the refrigerant isconducted by way of conduit 31 and branch conduits 32-32 to theevaporators 27 and 2S. After the refrigerant passes into the evaporatorsand expanded to carry olf heat, it is returned by way of branch conduits33-33 and conduit 34 to the upper portion of the accumulator, which ismaintained under a lower pressure. In its expanded state, therefrigerant is essentially in the form of a mixture of liquid and gas.The liquid ammonia drops by gravity downwardly into the accumulatorshell, while the gas is drawn ol by the suction line 4, which ismaintained under suction pressure by operation of the compressor 1 asindicated by the arrows in FIGURE 1.

From the foregoing, it will be seen that the amount of heat absorbed bythe evaporators determines the rate of flow of liquid refrigerantthrough the conduits 30-32 to the evaporators. The liquid level controlvalve 22 in turn responds to the delivery of liquid to the evaporatorsto advance corresponding amounts of high pressure liquid refrigerantfrom the receiver 11 to the accumulator I2 for recirculation through thesub-cooling coil, and through the motor to the accumulator shell.

Motor-Pump Operation The motor 18, as noted earlier, preferably is ofthe rotary positive displacement type, as distinguished from a turbinemotor, for example, which depends upon a velocity flow stream forenergization. The pump 20, similarly is of the positive displacementtype and is coupled in direct driving connection with the motor. In thepresent example, the motor and pump are both gear type spezeaostructures, as described later with reference to FIG- URES 3-5; however,it will be understood that various other combinations may be utilizedfor the same purpose, such as rotary vane pumps' and motors. In thepresent example, the cubic displacement per revolution of the pump issubstantially two times greater than the displacement of the motor whichis directly coupled to the pump.

As the float valve 22 opens to admit refrigerant to the accumulatorunder back pressure maintained in the receiver 11, the liquidrefrigerant ows by way of lines 13, 16 and 21, and through the motor 18,thus driving the pump 20 which is interposed in the conduits 3i) and 31leading to the evaporators 27 and 28. It will be understood that at thispoint the pressure of the refrigerant is reduced somewhat by theresistance of the motor; hence, the liquid refrigerant flowing from thereceiver il through the lines 13 and 16 is subcooled in coil 15 toprevent excessive flash gas in the motor and beyond. On the other hand,the refrigerant flowing by way of conduit 3i? from the accumulatortoward the evaporators is under lower pressure since the pressuredepends upon the gravity flow' produced by the liquid level in theaccumulator. Accordingly, as the low pressure refrigerant enters thepump by way of line 30, it is forced under slightly higher pressure byoperation of the pump into the conduit 31 and thus is advanced in apositive manner and at increased volume to the evaporators 27 and 28.The liquid-powered pump therefore substantially increases the ehciencyof the system', taking advantage of the energy of the pressurized liquidrefrigerant which circulates from the sub-cooling coil 15 to theaccumulator shell 25.

In order to permit the motor to be serviced, if this should becomenecessary after prolonged service, there is provided a branch conduit 35which by-passes the motor l from line 16 to line 21. This branch lineincludes a normally closed hand-operated valve 36. In addition, lines 16and 21 are each provided ywith similar normally open valves 37 and 38-on opposite sides of the motor. The valves 37 and 38 thus can be closedand valve 36 opened so as to by-pass the refrigerant, permitting normaloperation of the system when the motor 18 is de-' commissioned forservicing.

The pump 2.@ is also provided with a by-pass line 49, which permitsoperation of the system in a normal way when the pump is decommissioned.The bypass line 40 includes a check valve 41 which permits passage ofthe refrigerant inthe direction indicated by the arrow and which blocksthe flow in the opposite direction. The check valve 41 thus prevents therefrigerant from bypassing back tol the accumulator shell during pumpoperation but permits operation of the system by gravity when themotor-purnp unit is shut down for servicing.

Moreover, inthe event that low pressure refrigerant is.

flowing to the evaporators while an excess 'of liquid is stored in theaccumulator, the float valve Iwill not call for more liquid from thereceiver. In this event, the motor-pump unit will remain inactive, whilethe low pressure refrigerant simply by-passes the pump and advances tothe evaporators by gravity inthe conventional manner.

As described later with reference to FIGURES 3-5, the pump-motor unit 17includes packing glands or seals arranged to prevent leakage ofrefrigerant about the rotating shaft of the motor and pump. However, inthe event that the packing glands should eventually become worn,permitting leakage of refrigerant either from the pump or from themotor, there is provided a shaft housing joining the motor and pump andcompletely enclosing the shaft and seals. This housing converts themotor and pump into a completely enclosed, self-contained unit, which issealed against external leakage.

Inorder to carry off any refrigerant which may seep past the packingglands, there is provided an exhaust line 42 having an endcommunicating' with the shaft housing of the motor-pump unit and havingan opposite end in communication with the upper portion oftheaccumulator,

which is under partial vacuum, as notedea-rlier. The gasY which may leakinto the sht housing, as well as droplets of liquid ammonia entrainedtherein, are thus drawn by Vacuum from the shaft housing to theaccumulator, as indicated by the arrows. loss of refrigerant throughVleakage and prevents the escape of gas into the atmosphere in the caseof a leaking gland. In order to provide ready detection of such leakage,a sight glass, as indicated diagrammatically at 43, is inserted in theline 4Z.

Condensl'ng Cycle System The refrigerating system shown in FIGURE 2illus trates the principles of the invention as applied to an industrialsystem of the condensing cycle type. This ysystem also has a widevariety of uses, and is of particular advantage where lower temperaturesare required and Where space is limited, one example being commercialice cream machines, or as in lard or butter apparatus,-where relativelysmall-sized evaporators must be used. The condensing cycle system hasthe further advantage of eliminating oil from the low temperaturesecondary stage which communicates with the evaporators. The presence ofoil detracts from the efficiency of anyv refrigerating system, becausethe oil eventually forms a coating upon the internal surfaces of theevaporators; this coating acts as an insulating medium which inhibitsthe passage of heat through the evaporators.

Described with reference to FIGURE 2, the systemv in general comprises aprimary stage or circuit indicated generally at 44 and a secondary stageindicated at 45, the arrangement being such that the two circuits do notcommunicate with one another. instead, heat is absorbed bytheevaporators of the secondary stage and transmitted through aheatexchange arrangementto the primary stage.- The primary circuit or stageincludes a motor-driven compressor 46 which is connected by a highpressure line 47 to a condenser 4x8. Since the compressor, whichinvolves the use of lubricant, is interposed in the primary stage,lubricant which may escape `into the primary stage cannot find its wayinto the evaporators of the secondaryV stage. As noted previouslywithrespect to FIGURE l, the condenser 48 is water-cooled and is adapted tocool and liquify the compressed, high pressure refrigerant gas flowingfrom the compressor. From the condenser 48, the liquiiied ammonia ows byway of line 50 to a high pressure receiver 51 which provides headpressure for forcing the liquid refrigerant to the accumulator. Theliquid ammonia flows from ythe receiver 51 by way of line 52 and througha sub-cooling coil 53 within the shell of an accumulator, indicatedgenerally at 54;

After passing through the sub-cooling coil 53, the liquid refrigerantpasses by way of line 55 to the motor 18 of the motor-pump unit 17, thenby way of line 56 to a fioat valve, indicated generally at 57, which issimilar to valve 22 previously described with reference to FIG- URE l,which regulates the liquid level 53 within the accumulator shell. Thecircuit includes a suction line 59 extending from the upper portion ofthe accumulator to the compressor and arranged to Ymaintain a partialvacuum within the accumulator and return the heat-laden refrigerant gasback to the compressor 46. This completes the primary circuit; however,it should be understood at f this point that the high pressure liquidammonia drives the motor 18 as it advances to the accumulator under backpressure by operation of the float valve. In the present disclosure, thepump 2i? acts upon the low pressure refrigerant of the secondary stage,as explained below.

The secondary stage or system 45 essentially comprises a low temperaturecondenser or heat exchanger 6), a sump 6l, either contained within theheat exchanger or separated as shown, and one or more evaporators' 62.This system also may utilize liquid ammonia as a refrigerant or mayutilize other refrigerants for this purpose.

This arrangement prevents` In the present example, the low temperaturecondenser 60 comprises a tank having a header 63 at one end, the headerbeing divided into two compartments by a separator 64. Liquidrefrigerant under high pressure is fed by way of a conduit 65 from thebottom of accumulator 54 into the lower compartment 66 of theaccumulator. This liquid then ows from the lower compartment 66, throughthe elongated heat exchange coils 67 to the upper compartment 68 asindicated by the arrows. During passage through the heat exchange coils67, the liquid refrigerant absorbs heat from the gas within thecondenser 60, thus condensing the gas to liquid, and expands thendischarges into the upper compartment 68, primarily in the form of gas,with liquid entrained therein. This gas is returned to the accumulator54 by way of conduit 70 then is carried back to the compressor by way ofthe suction line 59.

Operation of Modified System As the float valve 57 opens to supplyrefrigerant to the accumulator 54 of the primary stage 44, the liquidrefrigerant under high pressure flows through the line 55 and energizesthe motor 18, which is interposed in this line, so as to drive the pump20, as described earlier with respect to the apparatus of FIGURE l.However, in this case, the chilled refrigerant flows by way of theconduit 71 of the secondary stage 45 from the low temperature condenser60 through the sump 61 interposed in conduit 71, and through the pump20, which is also interposed in the conduit 71. As noted with respect tothe system of FIGURE 1, the cubic displacement per revolution of thepump, in the present example, is substantially two times greater thanthe displacement of the motor.

It will be understood at this point that the sub-cooled refrigerantflowing from the coil 53 of the accumulator of the primary stage 44 isunder high pressure and provides sufficient kinetic energy (which isderived from the compressor) to drive the pump. On the other hand, thecooled refrigerant from the low temperature condenser 60 of thesecondary stage 4S is forced toward the evaporators 62 by the pump 20under less pressure but at increased volume, thus increasing theeiciency of the system. Upon entering the evaporators 62, the liquidrefrigerant expands and carries off heat, then is returned by way of theconduit 72 to the low temperature condenser or heat exchanger 60essentially in the form of gas and liquid.

As noted with respect to the recirculation system of FIGURE l, thepressure system also may be provided with a high pressure line (notshown) by-passing the motor 18, together with hand-operated valvespermitting operation of the system by gravity when the motor must beshut down for servicing. In this case, the pump 20 similarly is providedwith a by-pass line interposed in the low pressure conduit 71 andincluding a check valve to permit the low pressure fluid to ow bygravity to the evaporators when the motor is shut down.

As noted earlier with respect to FIGURE l, the present system is alsoprovided with an exhaust line or tube 73 having one end communicatingwith the shaft housing of the motor-pump unit, the tube having anopposite end connected to the top of the primary stage accumulator 54,Which is maintained under W pressure by operation of the compressor 46.The tube 73 may also be provided with a sight glass 74 for visualinspection. The exhaust line 73 thus maintains the shaft housing underlow pressure so as to carry off any refrigerant gas or liquid which mayleak into the housing through the shaft seal of the motor or pump. Inview of the fact that the pump is in communication with the secondarystage, While the exhaust line 73 communicates with the primary stage,the same kind of refrigerant must be used in both stages to preventcontamination through intermingling of the refrigerant.

E Motor and Pump Construcion As noted earlier, the motor-pump unitdisclosed in' FIGURES 3-5 has been selected to illustrate a typicalexample of a rotary type motor and pump suitable for use in the presentinvention. It should be specifically noted that the gear type motor andpump is used for purposes of illustration only, and that any one of theseveral well known types of positive displacement pumps and liquidmotors may -be substituted. As best shown in FIGURE 4, the motor 18comprises two intermeshing gears, one of the gears being coupleddirectly to the pump. The pump 20 also comprises a pair of intermeshinggears, the pump and motor both operating under positive displacement,the cubic displacement of the pump preferably being in two-to-one ratiowith the motor, as pointed out earlier.

The motor 18 comprises a housing 75 having a mounting bracket 76 boltedas at 77 to a base 78, which also mounts the pump 20. The motor housing75 includes an oval-shaped cavity 80 (FIGURE 4) which encloses the gearsS1 and S2 and provides a running tit with the teeth thereof. The uppergear 81 is keyed to a drive shaft S3, while the lower gear tid is keyedto an idler shaft 34. As viewed in FIGURE 3, the right hand ends of theshafts 83 and 34 are journalled in a bearing cap 85 which is bolted asat 86 to the gear housing 75. The bearing cap has a pair of blind boreswhich include bushings S7 for the shafts. The lefthand side of the gearhousing 75 is provided with a second bearing cap d3 also bolted `as at86 to the gear housing. The idler shaft S4 of the lower gear isjournalled in a blind bore (not shown) while the drive shaft 83 isjournalled in and projects through the bearing cap, being keyed as at tothe drive element 91 of a exible coupling indicated generally at 92. Apacking gland 93 within the bearing cap SS embraces the drive shaft 03and is held under pressure by a retainer ring 94 which is threaded intothe bearing cap 88.

The pump 20 is similar to the motor, comprising in general a pumphousing95 having a mounting bracket 6 bolted as at 97 to the base 78 in spacedrelation to the motor. The housing 95 includes a cavity 9S enclosing theupper and lower pump gears and 101. rihe upper gear 100 is mounted upona drive shaft 102 coaxial with the motor drive shaft 83, while the lowergear is mounted upon an idler shaft 103. The left hand end of the pumpshafts are journalled in bushings 10d- 104 which are mounted in blindbores formed in the bearing cap 105; the cap is bolted as at 106 to thepump casing 95. The opposite end of the drive shaft 102 passes through abearing cap 107, which is also bolted as at 106 to the pump housing 95.A packing gland 108, having an adjustable retainer ring 110 surroundingthe drive shaft 102, provides a seal about the shaft. The opposite endof the idler shaft 103 is journalled in a blind bore formed in thebearing cap 107. The outer end of the drive shaft 102 is keyed as at 111to the driven elements 112 of the flexible coupling previously indicatedat 92. This coupling provides a direct connection between driven anddrive shafts and compensates for the minor deviations in alignment ofthe shafts. Since the coupler is conventional, certain details ofconstruction have been omitted.

The shaft housing 113 comprises a generally cylindrical sleeve 114,having anges 11S-115 at opposite ends, which are bolted as at 116 -tothe bearing caps 88 and 107 of the motor and pump. The exhaust line,previously indicated at 42 or 73, communicates with a bore 117 formed inthe lower portion of the sleeve 114, such that liquid refrigerant drainsby gravity to the exhaust line. The upper portion of lthe sleeve 114 mayinclude an opening 118 which is sealed off by a cover plate 120 (FIGURE3) secured in place by screws 121. This plate may be removed forservicing the packing glands 93 and 10S should this become necessaryafter prolonged service.

As shown in FIGURE 4, the high pressure liquid refrigerant is advancedto the motor by way of the bore 122 of the motor housing 75, whichincludes a fitting or adaptor 123 for the high pressure lines lo or 55,-previously described with reference to FIGURES l and 2. The highpressure refrigerant rotates the motor gears in the direction indicatedby the arrows in FIGURE 4, and is exhausted by Way of an exhaust port124. This port includes similar fittings or adaptor 125 to which isconnected the conduit Z1 or 56 (FIGURE-l or 2) leading to the floatvalve of the accumulator. It will be noted that the pump components aresubstantially greater in size than the motor components to provide thedesired ratio-of pump displacement over motor displacement as pointedout earlier.

Having described my invention, I claim:

1. In a refrigerating system, an accumulator, a first conduit adapted tosupply liquid refrigerant under high pressure to the accumulator, liquidlevel control means associated with the accumulator and adapted tocontrol the flow' of liquid refrigerant through said first conduit intothe accumulator and to maintain the refrigerant at a given liquid levelin the accumulator, an evaporator, a second conduit connected to theevaporator and adapted toY supply liquid refrigerant under relativelylow pressure to the evaporator, means adapted to maintain a suctionpressure in the accumulator above said liquid level, a positivedisplacement rotary liquid-powered motor interposed in said firstconduit and adapted to be driven by the liquid refrigerant which isadvanced under high pressure to the accumulator under control of saidliquid level control means, and a positive displacement rotary liquidpump in direct driving connection with said motor and interposed in saidsecond conduit, said pump providing positive displacement of liquid perrevolution of the pump at a rate which is substantially greater than thepositive displacement per revolution of the motor, said pump adapted toadvance refrigerant liquid under low pressure toward the evaporator inresponse to energization of said liquid-poweredl motor, the liquidrefrigerant being advanced by said pump to the evaporator at a ratesubstantially greater than the flow of refrigerant under high pressurethrough said first conduit and motor to the accumulator.

2. In a refrigerating system, an accumulator, a first conduit adapted tosupply liquid refrigerant under high pressure to the accumulator, aliquid level control valve associated with the accumulator and adaptedto control the flow of liquid refrigerant through said rst conduit, intothe accumulator and to maintain the refrigerant at a given liquid levelin the accumulator, an evaporator, a second conduit connected to theevaporator and adapted to supply liquid refrigerant under relatively lowpressure to the evaporator, means connected to the accumulator above theliquid level thereof and adapted to maintain a suction pressure abovesaid liquid level, a positive displacement liquid-powered rotary motorinterposed in said lirst conduit and adapted to be energized by theliquid refrigerant which is advanced under high pressure to theaccumulator under control of said liquid level control means, a positivedisplacement rotary liquid pump interposed in said second conduit,driving means connecting the motor and pump, and a closure elementsurrounding said driving means and joining the motor and pump in sealedrelationship, said pump providing positive displacement of liquid perrevolution of the pump at a rate which is substantially greater than thepositive displacement per revolution of the motor, said pump adapted toadvance refrigerant liquid under low pressure through the second conduittoward the evaporator in response to energization of said liquid-poweredmotor, the liquid refrigerant being advanced by said pump to theevaporator ltd at a rate substantially greater than the flow ofrefrigerant under high pressure through said first conduit and motor tothe accumulator, and a third conduit extending from said closure elementto the accumulator and communieating with the space above the level ofthe refrigerant therein, said conduit adapted to exhaust leakingrefrigerant from said closure element and to deliver the same to theaccumulator.

3. In a refrigerating system, an accumulator, a firstl conduit adaptedto supply liquid refrigerant under high pressure to the accumulator,liquid level control means associated with the accumulator and adaptedto control the flow of liquid refrigerant through said rst conduit intothe accumulator and to maintain the refrigerant at al given liquid levelin the accumulator, an evaporator, a second conduit connected to theevaporator and adapted to supply liquid refrigerant under relatively lowpressure to the evaporator, means connected to the accumulator above theliquid level thereof and adapted to maintain a suction pressure abovesaid liquid level, a positive displacement rotary liquid-powered motorinterposed in said first conduit and adapted to be energized by theliquid refrigerant which is advanced under high pressure to theaccumulator under control of said liquid level control means, a positivedisplacement rotary liquid pump interposed in said second conduit, saidpump adapted to' advance refrigerant liquid yunder low pressure throughthe second conduit toward the evaporator in response to energization ofsaid motor, said pump providing positive placement of liquid perrevolution of the pump at a rate substantially greater than thepositivey displacement per revolution of the motor, a drive shaftconnectingsaid motor to said pump, a shaft housing surrounding the saiddrive shaft and having opposite ends secured in sealing engagement withthe motor and pump, and a third conduit communicating with and extendingfrom said shaft housing to the accumulator and communicating with thespace under suction pressure above the level of the refrigerant therein,said conduit adapted to exhaust leaking refrigerant from said shafthousing and to deliver the same to the accumulator.

4. In a condensing cycle refrigeration system, a primary stage having anaccumulator, a rst conduit adapted to supply primary stage liquidrefrigerant under pressure to the accumulator, a secondary stageincluding an evaporator, a second conduit adapted to advance secondarystage liquid refrigerant to the evaporator, a liquidpowered motorinterposed in said rst conduit and adapted to be energized by theprimary stage liquid refrigerant which is advanced through said firstconduit to the accumulator, a pump interposed in said second conduitwhich advances secondary stage liquid refrigerant to the evaporator,said pump in driving connection with the motor and adapted to advancesecondary stage liquid refrigerant under loW pressure toward theevaporator in response to energization of said liquid-powered motor bythe primary stage liquid refrigerant.

5. In a condensing cycle refrigeration system, a primary stage having anaccumulator, a first conduit adapted to supply primary stage cooledliquid refrigerant under pressure to the accumulator, a secondary stageincluding a condenser adapted to confine secondary stage liquidrefrigerant, means for circulating primary stage liquid refrigerant fromthe accumulator through the condenser, said condenser adapted to provideheat exchange between the primary and secondary stage refrigerant, anevaporator in said secondary stage, a second conduit communicating withthe said condenser adapted to advance secondary stage cooled refrigerantfrom the said condenser to the evaporator, a liquid-powered motorinterposed in said first conduit adapted to be energized by the primarystage liquid refrigerant which is advanced to the accumulator, a pumpinterposed in said second conduit which advances secondary stage liquidrefrigerant to the evaporator, a driving connection between the motorand pump, said pump adapted to advance secondary stage liquidrefrigerant under pressure toward the evaporator in response toenergization of said liquid-powered motor by the primary stage liquidrefrigerant.

6. In a condensing cycle refrigeration system, a primary stage having anaccumulator, a first conduit adapted to supply primary stage liquidrefrigerant under pressure to the accumulator, liquid level controlmeans associated with the accumulator and adapted to control the iiovvof refrigerant through said rst conduit, a secondary stage including alow temperature condenser, heat exchange means in said low temperaturecondenser, said condenser adapted to confine secondary stage liquidrefrigerant in contact with said heat exchange means, means forcirculating primary stage liquid refrigerant from the accumulator andthrough the heat exchange means of the low temperature condenser, anevaporator in said secondary stage, a second conduit communicating withthe said low temperature condenser adapted to advance said secondarystage liquidrefrigerant from the said condenser to the evaporator, -aliquid-powered motor interposed in said first conduit and adapted to beenergized by the primary stage liquid refrigerant which is advanced tothe accumulator, a pump interposed in said second conduit which advancesliquid secondary stage refrigerant from the low temperature condenser tothe evaporator, a driving connection between the motor and pump, saidpump adapted to advance secondary stage liquid refrigerant under lowpressure toward the evaporator in response to energization of saidliquid-powered motor by the primary stage liquid refrigerant.

7. In a condensing cycle refrigeration system, a primary stage having anaccumulator, a first conduit adapted to supply primary stage liquidrefrigerant under pressure to the accumulator, liquid level controlmeans associated with the accumulator and adapted to control the iiow ofrefrigerant through said rst conduit and to maintain the refrigerant ata given liquid level therein, means for maintaining the upper portion ofthe accumulator under suction pressure, `a secondary stage including anevaporator, a second conduit adapted to advance secondary stagerefrigerant to the evaporator, a liquid-powered motor interposed in saidlirst conduit and adapted to be energized by said primary stage liquidrefrigerant which is advanced through said first conduit to theaccumulator, a pump interposed in said second conduit which advancessecondary stage liquid refrigerant to the evaporator, a drive elementconnecting said motor and pump, a housing surrounding said drive elementand secured in sealed engagement with the motor and pump, and an exhaustconduit extending from said shaft housing to the accumulator above thelevel of the liquid refrigerant in the accumulator and adapted toevacuate leaking refrigerant from said housing, said pump adapted toadvance secondary stage liquid refrigerant through said second conduitto the evaporator upon energization of the motor in response toadvancement of primary stage liquid refrigerant high pressure throughthe first conduit to the accumulator.

References Cited in the ile of this patent UNTED STATES PATENTS1,433,733 Lindsay Oct. 3l, 1922 1,944,472 Sloan 2 Jan. 23, 19342,156,096 Robinson Apr. 25, 1939 2,519,010 Zearfoss Aug. 1S, 19502,754,665 Brandt July 17, 1956 2,775,204 Batten Dec. 25, 1956 2,844,945Mufl'ly July 29, 1958

